Torque and speed responsive system



May 3, 1966 R. w. BRUNDAGE 3,248,913

TORQUE AND SPEED RESPONSIVE SYSTEM Filed March 12, 1964 2 Sheets-Sheet 1 May 3, 1966 R. w. ERUNDAGE 3,248,913

TORQUE AND SPEED RESPONSIVE sYsTEM Filed March 12, 1964 2 Sheets-Sheet 2 f5 7 7 /ya /32 l I NVE NTOR. @men/@Win45 United States Patent O 3,248,913 TORQUE AND SPEED RESPONSIVE SYSTEM Robert W. Brundage, Belnor, Mo., assigner to Emerson Electric C0., St. Louis, Mo., a corporation of Missouri Filed Mar. 12, 1964, Ser. No. 351,474 8 Claims. (Cl. 68-133) This invention relates to machines in the nature of clothes washing machines. It has particular application and will be described in connection with clothes washing machines of the vertical agitating type and the horizontal tub type. Its usefulness, however, is not confined to clothes washing machines.

In clothes washing machines known heretofore, an increase in the load either produces no change in the speed of agitation, or decreases that speed. As a result, the agitator speed (or tub speed in the horizontal tub type) represents a compromise between the slow speed at which a light load can be Washed without undue abuse and tangling of the clothes and the high speed essential to produce circulation of the clothes in a heavy load. Under these conditions, delicate fabrics tend to be over-agitated; bulky clothes tend to slump around the agitator or along the bottom of the tub and be abraded but not well washed.

Provision has been made heretofore for manual presetting of agitator speed to accommodate different types of loads. However, one problem which persists arises from the fact that the proper agitation is a function both of the type and of the amount of clothes to be washed. Thus, nine pounds of cotton bed sheets require more agitation than nine pounds of nylon underwear, but the latter takes more agitation than two pounds of cotton handkerchiefs.

One of the objects of this invention is to provide an automatic load compensating system for machines in the nature of clothes washing machines.

Another object is to provide such a system in which the torque and speed of the agitating means, or functions of both, are sensed simultaneously, whereby a system is provided in which the speed of agitation tends to increase as the torque on the agitator increases, and vice versa.

In accordance with this invention, generally stated, a driving system is provided for a machine in the nature of a clothes washing machine, in which provision is made for sensing, simultaneously, some function of the speed and some function of the torque of an agitator. The agitator may be of the oscillating vertical type or the planetary vertical type or a reciprocating vertical type, or it may be the tub itself, as in the horizontal rotating tub type of wash machine.

In any case, the sensing device is arranged to tend to increase the speed of the agitating means, within limits, as the torque on the agitating means increases, and vice versa.

In the preferred embodiment shown and described, the drive system takes the form of a hydraulic motor driven by a constant delivery hydraulic pump, and a bypass arrangement between the pump and motor, governed by a control valve responsive to both the torque and speed of the motor. It will be apparent to those skilled in the art in the light of the following description that similar results may be obtained by the use of a variable delivery hydraulic pump, but the constant delivery pump has certain advantages.

It is also possible to accomplish the objects of this invention electrically and mechanically. However, the hydraulic system offers certain important advantages in simplicity, nicety of control, dependability, and compactness, which are not attainable by other means.

In the drawing, FIGURE 1 is a schematic representation of the preferred embodiment of this invention;

"ice

FIGURE 2 is a sectional view of a control valve suitable for use in the system shown in FIGURE 1, showing the valve in a condition at which the hydraulic motor is being driven at full speed;

FIGURE 3 is a sectional View of the valve shown in FIGURE 2, showing the valve in a condition at which the gydraulic motor is being driven at an intermediate spee FIGURE 4 is a schematic representation of another embodiment of this invention; and

FIGURE 5 is a sectional view of a control valve suitable for use in the system shown in FIGURE 4.

Referring now to FIGURES 1-3 of the drawing for the preferred illustrative embodiment of system of this invention, reference numeral 1 indicates a wash machine of the vertical oscillating agitator type, with a tub 2, and an agitator 3, driven by an agitator shaft 4, which in turn is driven by an oscillating type hydraulic motor 5. The hydraulic motor 5 is connected by a hydraulic line 6 to the discharge side of a Aconstant delivery hydraulic pump 7, connected to be driven at a substantially constant speed by an electric motor 8. A supply line 9 leads from a hydraulic fluid reservoir 10 to the intake side of the hydraulic pump 7. A return line 11 leads from the low side of the hydraulic motor 5 to a control valve 20. A reservoir line 12 leads from the control valve 20 to the reservoir 10. A control line 13 is connected, in parallel with the hydraulic line 6, to the discharge side of the hydraulic pump, and to the control valve 20. A bypass line 14 connects the control valve 20 with the reservoir 10, at the opposite end of the control valve from the reservoir line 12.

Referring now to FIGURES 2 and 3, the control valve 20 includes a valve -body 21 with an elongated bore 22, closed at one end Vby a Wall 23, and internally threaded at its other end, as indicated at 24. In the embodiment shown, the wall 23 has, integral with its inner side, a post or lixed piston 25. The piston 25 is centered in the bore 22 and projects axially toward the threaded end of the bore.

The inner wall of the bore 22 is interrupted by four annular channels or cavities: a 'bypass cavity 31, a control cavity 32, a return cavity 33 and a reservoir cavity 34. Ports 41, 42, 43 and 44 communicate between the cavity 31 and bypass line 14, cavity 32 and control line 13, cavity 33 and return line 11 and cavity 34 and reservoir line 12 respectively. The cavities 33 and 34 dene between them a land 45.

A helical spring is mounted around the piston 25, with one end bearing against the inner face of the wall 23, and its other end bearing against the end face of a valve section 62 of a spool 60. The spool 60 has a head 61, of a diameter closely but slidably to fit in the bore 22, the valve section 62, of the same diameter as the head section, at the opposite end of the spool, and a reduced section 63 intermediate the valve and head section. The spool 6i) has an axially extending hole from and through the valve section end face to the head section 61, defining within the spool a cylinder 65. A diametric passage 66 extends through the restricted section 63 and communicates with the cylinder at the head end of the restricted section and cylinder. The cylinder 65 closely Ibut slidably receives the piston 25.

An adjusting plug 70 is threaded into the threaded section 24 of the valve body. The plug 70 has a knob 71, an externally threaded section 72, a smooth barrel section 73, an orifice shoulder 74 and a stop post 75. The stop post projects axially from the center of the inner end of the plug 7 (l.

The shoulder 74 and the edge of the land 45 adjacent it dene between them an orifice 55.

Merely by way of illustration, and not of limitation, the hydraulic pump 7 can have av constant output of two gallons of hydraulic fluid per minute. The electric motor 8 can be a `1/2 horsepower single phas'eLA.C. motor. The spool 60, at the read and valve sections can be 1/2 inch in outside diameter, which provides a face area for the head of approximately .196 square inch. The spring 50 can exert a pressure of two pounds in the initial position. The area of the orifice opening can be about .032 square inch. The cross-sectional area of the piston 25 can be about .0l2 square inch, so that the area of the face of the head section of the spool is approximately sixteen times the area of the head of the piston 25. Under these circumstances, a pressure drop across the orifice of on the order of eleven pounds per square inch will start to move the spool against the bias of the spring 50. The size of the various lines carrying the hydraulic fluid is not important, as long as they are large enough to handle the predetermined volume of hydraulic fluid without excessive pressure drop. A satisfactory range of agitator speeds may be from thirty oscillations per minute to forty-five oscillations per minute, Ibut this, of course, can be varied to meet the particular conditions of load and characteristics of the wash machine.

While the hydraulic motor 5 has been described as being of the oscillating type, it is clear that a rotary type motor either driving a planetary type vertical agitator or a tub will work equally well and the remaining elements of the system can be identical to those described above.

In explaining the operation of the preferred embodiment of device of this invention, there are several things to be borne in mind. First, within the limits imposed by leakage and the strength of the materials, the speed of the hydraulic motor will vary directly as the volume of fluid delivered to it. For example, the motor will run twice as fast when it is supplied with two gallons per minute of fluid, as it does when it is supplied with one gallon per minute. Second, absent any back pressure on the motor, the pressure of the fluid delivered to the motor will vary as a direct function of the torque on the motor. Third, any back pressure on the motor merely reduces the effective driving pressure by the amount of the back pressure. Fourth, a pressure drop across an orifice of fixed size with a homogeneous liquid, is a function of the square of the fluid flow through the orifice, e. g. a two fold increase in the volume of hydraulic fluid through an orifice signifies a four fold increase in pressure drop.

In the operation of the device shown in the drawing and described, the adjusting plug 70 is turned to the desired setting, which produces predetermined clearance between the shoulder 74 and the edge of the land 45, i.e., fixes the size of the orifice 55. The hydraulic pump is started, to drive the hydraulic motor. Assuming that there are no clothes in the washing machine, the load on the hydraulic motor will be very light, i.e., the torque on the agitator shaft will be low. Therefore, as has been indicated, the pressure build-up on the high or power side of the hydraulic motor will be very low. This means that the differential pressure on the line 13 will be low, but the pressure in the return line 11, produced by the restriction of the orifice 55, will be relatively high. 'I'he strength of the spring 50 is such that the pressure in the chamber ybetween the head y61 of the spool and the shoulder 74 of the adjusting plug, acting on the full area of the face of the spool head, will move the spool, against the bias of the spring 50, to a position such as the one shown in FIGURE 3, in which the reduced section 63 of the spool forms a passageway between the control line 13 and the bypass line 1-4, permitting hydraulic fluid to be bypassed to the reservoir 10. This reduces the volume of hydraulic fluid to the hydraulic motor, hence reduces the speed of the motor. It is apparent that a balance, for a given idle load of the wash machine, will be established almost instantaneously.

If, now, some clothes are put into the machine, the

torque on the shaft 4 will increase, so the pressure on the high side of the hydraulic motor will increase. This increased pressure will also be manifest in the cylinder 65 between the end of the piston 25 and the head 61. This will tend to throw the spool 60 in a direction toward the stop 7S, which will restrict the bypass passage, thus reducing the amount of hydraulic fluid which is bypassed, and increasing the flow of hydraulic fluid to the motor.

The increased flow of hydraulic fluid to the motor will, however, increase the pressure across the orifice 55 as a function of the square of the flow. This, then, tends to move the spool 60 away from the stop 75, and a new balance is reached.

With a very heavy load, a constant delivery pump, and a system which admits of the .accommodation of high pressures, it can be seen that after the maximum back pressure of the hydraulic fluid on the spool 60 has been reached, .e. the pressure at which full volume of the fluid passes, further increases in pressure in the high side of the pump and motor will merely bias the spool more strongly against the stop post 75, in the position shown in FIGURE 1. Normally, this situation will not obtain, because the load is now so great that the speed of agitation is beyond the point of further control, having reached the maximum.

It can be seen that if the orifice 55 is opened, the back pressure will be less, and the motor will be run at a higher speed than if the orifice is narrowed. Thus, the speed of the `agitator at low and moderate loads can be varied very easily. The top speed is fixed by the capacity of the pump.

In the embodiment of system shown in FIGURES 4 and 5, the control valve is positioned on the high side of the hydraulic motor, rather than on the discharge side. In particular, `a control valve is provided, With a body 101 and elongated bore 102, terminating at one end within the body 101 .and threaded internally at its other end, as indicated at 104. The inner wall of the bore 102 is interrupted by four annular channels or cavities: a bypass cavity 131, a control cavity 132, a motor supply cavity 133 and a fluid supply cavity 134. The cavities 133 and 134 define between them a land 145. The bore 102 is reduced in diameter between the cavities 131 and 132, to closely but slidably accommodate a reduced end section 161 of a spool 160.

A bypass line 114 communicates with the bypass cavity 131 and with the reservoir 10. The control line 113 communicates with the control cavity 132 and with a discharge line 106 from the hydraulic pump 7. The discharge line 106 also communicates With the fluid supply cavity 134. A motor supply line 108 communicates with the motor supply cavity 133 and with the high side of the motor 5.

The spool 160, in this embodiment, has a head section 162 with a central cup shaped recess 163 within which is seated one end of ra helical spring 150. The other end of the helical spring bears on an adjusting plug 170 which is threaded into the threaded section 104 of the valve body. The adjusting plug 170 has a knob 171, by which the plug can be turned manually to move it in and out of the valve body, an externally threaded section 172, and a Ismooth barrel section 173 which defines, with a radial face 175, a shoulder 174.

The shoulder 174 and the edge of the land 145 adjacent it define between them an orifice 155.

In the operation of the embodiment of system shown in FIGURES 4 and 5, assuming that the wash machine has no load in it, that the pump 7 is a constant delivery pump, driven by a substantially constant speed motor, and that the spool 160 is in -the position shown in FIGURE 5, the pressure drop across the orifice will be very high, i.e., the pressure on the high side of the motor will be low. The relatively high pressure in the line 106 will be manifest in the chamber defined between the radial end of the restricted section 161 of the spQQl. 1.6.0 and the inner end of the bore 102. The pressure differential between the two ends of the spool 160 will cause the spool to move, against the bias of the spool 160 to a position at which the radial face of the restricted section 161 clears the restricted section of the bore 102, thus to put cavities 132 and 131 into communication, and admit fluid from the pump to bypass line 114 to the reservoir.

When a load is put in the wash machine, the torque on the motor 5 increases, also pressure in the line 108, hence in the chamber defined between the head end of the spool and the face 175 of the adjusting plate, the pressure differential across the orifice 155 will decrease, and, by virtue of the bias of the spring 150 and the larger cross-sectional area of the head end of the spool 160 than that of the restricted section 161, the spool Will be biased, against the pressure in the lines 106 and 113, in a direction away from the adjusting plug, which will tend to restrict and ultimately to block completely the communication between the cavities 132 and 131. This restriction and ultimately the closing of the communication between the cavities 132 and 131 will, of course, increase the amount of fluid supplied to the motor, hence the speed of the motor.

The embodiment of system `shown in FIGURES 4 and 5 has certain disadvantages over the preferred embodiment. For example, in those machines in which there is likely to be high inertia, the downstream (preferred) control provides a braking action, since the discharge from the hydraulic motor is through the orifice 55, whereas in the embodiment shown in the upstream control (FIGURES 4 and 5), the discharge `from the hydraulic motor is to the reservoir, which will tend to produce cavitation.

The preferred embodiment of this invention described has numerous advantages of simplicity, efficiency, compactness and dependability over other systems which might be used to accomplish the described result, but other means besides the second embodiment may be employed. For example, the movement of the spool of either embodiment could be used to control the output of a variable output hydraulic pump. The results could be obtained electrically by using a differentially compounded D.C. motor with series iield turns in a direction to buck the field flux, to drive the agitator shaft.

A mechanical arrangement might also be used, wherein a torque sensing device, such as a torsion bar, could be used to control it-he ope-ration of ia Reeves drive or the like.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. A wash machine comprising agitating means, a hydraulic motor, having a Ihigh and a low side, connected to drive said agitating means, a hydraulic pump having an intake side and a discharge side, said discharge side being connected to the high side of said motor to supply hydraulic fluid to said hydraulic motor, and control means connected hydraulically to the discharge side of said pump and to the low side of the motor, said control means including an orifice communicating with the low side of the motor, said oriiice havin-g a hydraulic fiuid pressure differential across it from a high side to a low side of the orifice, a movable valve member responsive to the pressure on the high side of said orifice for movement in one direction and to the pressure on the discharge side of said pump for movement in t-he opposite direction, said valve being connected to control the flow of hydraulic fluid to said motor whereby movement of said valve in response to increased flow of fluid tends to decrease the said flow and movement in response to increased pressure on the discharge side of said pump tends to increase said flow.

2. A clothes Washing machine comprising an agitator, a hydraulic motor connected to drive said agitator, a hydraulic pump connected to supply fluid under pressure to said motor and control means responsive to the pressure of iiuid supplied the motor by the pump and to lthe volume of tiuid through the motor, connected to increase the fioW of fiuid through the motor in response to increase in the pressure from the pump to the motor.

3. A clothes washing machine comprising an agitator, a hydraulic motor connected to drive said agitator, a hydraulic pump connected to supply hydraulic Ifluid under pressure to said motor, and control means connected to the discharge side of said pump and to the return side of said motor, said control including metering means for determining the volume of flow of said hydraulic `fluid and translating said fiow to a -force tending to reduce the volume of flow, and means responsive to the pressure of said iuid from said pump and translating said pressure to a force tending to increase the volume of flow, said forces being interconnected to increase said iow as the said pressure increases, as a function of a sensed ratio of torque to speed.

4. A clothes washing machine comprising an agitator, a hydraulic motor connected to drive said agitator, a hydraulic pump connected to supply hydraulic lfluid under pressure to said hydraulic motor, a control connected to the pressure side of said hydraulic pump `and to the low side of said hydraulic motor, said control comprising a spool valve having a valve body, a shiftable spool Within said valve body, an orifice Within said valve body and communicating with a chamber deiined in part by an end of said spool, said chamber communicating with the low side of said hydraulic motor, Iand a second chamber, communicating with the discharge side of the hydraulic pump and with an axially spaced portion of the spool whereby pressures in said chambers tend to move the spool in opposite directions, the effective force of iiuid in the orifice chamber against said spool being multiplied with respect to the force of the ffluid in the second chamber, and means responsive to movement of said spool for controlling the amount of hydraulic fluid delivered by said pump to said motor.

5. A hydraulic system responsive to speed and torque, comprising a constant delivery hydraulic pump, means for driving said hydraulic pump at -a substantially constant speed; a hydraulic motor connected to be supplied With hydraulic fluid under pressure by said hydraulic pump, and control means comprising a valve lhaving a shiftable mem-ber connected with said hydraulic system to be biased in one direction by a force which is a function of the volume of ow of hydraulic fluid through said motor, and biased in the opposite direction by a force which is a funetion of the pressure of the fluid supplied the motor by the pump, and means controlled by the shiftable member, for regulating the flow of Huid from said pump to said motor.

6. A hydraulic system responsive to speed and torque, comprising `a constant delivery hydraulic pump having an intake side and a discharge side, means for driving said hydraulic pump at a substantially constant speed; a hydraulic motor having a high side Iand a low side, said high side being connected to the discharge side of the pump to be supplied with hydraulic fluid under pressure by said hydraulic pump, and control means comprising a spool valve having a body and -a shiftable spool within said body, said body having a chamber communicating with a radial surface of said spool, with an orifice and in series with the low side of said hydraulic motor whereby the pressure of fluid in said chamber is :a function of the ow of fluid through said orifice, a second chamber communicating with a second radial surface of said spool spaced axially from said iirst surface whereby a force :applied to said second surface opposes a force applied to said first surface, said second chamber communicating with the discharge side of said hydraulic pump, said valve body having a bypass cavity and said spool having a bypass passage-defining section communicating with said discharge side of the hydraulic pump and being adapted to move toward and away from communication with said bypass cavity las said spool moves in response to pressures in said first and second cavities respectively.

7. The system of claim 6 wherein the ori-lice is defined by a fixed edge and Va movable shoulder, and means are provided for selectively moving said shoulder relativew to said edge. i

8. A clothes Washing machine comprising agitating means, a hydraulic motor connected to said agitating means, a hydnaulic pump connected to supply iuid under pressure to said hydraulic motor, a by-pass flow control valve connected to the pressure side of said pump and control means on said by-pass valve `adapted to decrease the volume of fluid by-passed from said pump as said pressure increases.

References Cited by the Examiner UNITED STATES PATENTS Vickers 60--52 Baade 68-23 X Patch 60-52 Barbulesco et al 68-23 X Bracken et al. 68-23 X Elliott et al. 68--12 Sones et a1. 68-23 X WILLIAM I. PRICE, Primary Examiner.

WALTER SCHEEL, Examiner. 

2. A CLOTHES WASHING MACHINE COMPRISING AN AGITATOR, A HYDRAULIC MOTOR CONNECTED TO DRIVE SAID AGITATOR, A HYDRAULIC PUMP CONNECTED TO SUPPLY FLUID UNDER PRESSURE TO SAID MOTOR AND CONTROL MEANS RESPONSIVE TO THE PRESSURE OF FLUID SUPPLIED THE MOTOR BY THE PUMP AND TO THE VOLUME OF FLUID THROUGH THE MOTOR, CONNECTED TO INCREASE THE FLOW OF FLUID THROUGH THE MOTOR IN RESPONSE TO INCREASE IN THE PRESSURE FROM THE PUMP TO THE MOTOR. 